1. Field of the Invention
The present invention relates generally to a device for holding and moving stones with suction forces, and in particular to a suction device that allows for minute distance adjustment, fixed-step advancing, and orientation adjustment between stone workpieces.
2. The Related Art
It is common in stone industry or construction industry to move and properly position heavy stone workpieces, such as marble blocks. This is usually done with suction device that applies a suction force to the stone workpieces for picking up and conveying the stone workpieces.
However, the conventional devices can only roughly position the suction-retained stone at an approximately location, and location adjustment is usually done manually with visual inspection. This makes it very difficult to precisely position the stones, especially to provide a precise gap between two stones or two stone slabs. Imprecise positioning of stones may deteriorate appearance of a finished job and even causes property damage and casualty.
A distance adjustable suction device is available, which is shown in FIG. 1 of the attached drawings. The suction device, generally designated with reference numeral 1, comprises first and second suction cups 10, 11, which are connected together by toothed racks 12 extending therebetween. First ends of the racks 12 are fixed to the first suction cup 10, while the other ends form teeth. A rotary handle 13 is rotatably mounted to the second suction cup 11 and comprises ratchet pinions 131 rotatably supported thereon. The ratchet pinions 131 matingly engage the teeth of the racks 12, respectively. By repeatedly and reciprocally rotating the handle with respect to the second suction cup 11, the ratchet pinions 131 that engage the racks 12 drive the racks 12 to move the first suction cup 10 with respect to the second suction cup 11 in a step by step manner. Thus, the distance between the first and second suction cups 10, 11 can be adjusted.
However, since the distance moved by a step of the racks 12 induced by the handle 13 is determined by the pitch of the teeth of the racks 12. It is not possible to do distance adjustment of a fraction of one step of the racks 12. Thus fine adjustment is in general very difficult, if not impossible.
Further, the arrangement of the racks 12, which are generally rigid, between the first and second suction cups makes it not possible for applications where the first and second suction cups are attached to stones that are at different levels, or that are of an inclined spatial relationship.
Thus, it is desired to have a suction device for stones that overcomes the above-discussed problems of the conventional devices.